Millions of americans bracing for the impact, everything from stalled trains and planes to tornadoes. And here is the map. An area from the florida panhandle to new york, under a severe weather warning. Abc's steve osunsami is outside atlanta tonight in adairsville, georgia, where one powerful tornado has already torn through town. Reporter: An hour north of atlanta, an amazing picture, the sky was falling. We've got debris flying to the left and center of this system. The sirens have been going off here. The wind is kicking up, along with the rain. Again, a funnel crossing the interstate here in adairsville. Reporter: Witnesses here say the tornado was on the ground, churning through homes, office buildings and factories for more than 20 minutes. Scientists think it was an ef-2 or greater, with wind speeds more than 125 miles an hour. Please take safe shelter for us right now. Get in the center portion of your home. A basement if you have it. Reporter: In calhoun, georgia, homes were leveled. At this factory in adairsville, workers scrambled for cover. Neighbors had to rescue families trapped inside their homes. One man was killed. There was no warnings, no nothing. Reporter: We talked with the family of the man who tied. They were at home looking for a lost pet. Jessica cantrell told us she can't bear to look. I wouldn't anybody else to look at this. Ha that's going to be able to get back on your feet. Reporter: I'm sorry. The tornado left behind what looked like a junkyard, with twisted semitrailers, more than 100 cars flipped by the end. Travis richardson was in his 18-wheeler when the tornado lifted his truck off the ground and threw it off the road. I couldn't believe it picked up my truck and flipped it over like that. I can't believe it. Reporter: The storm still stretches more than 900 long miles, and as it marched across the country, it brought high winds to texas. In missouri, flash flooding. And then winds that knocked down 50 train cars. Further north in green county, indiana, dozens of homes were damaged or destroyed. Today's misery reached quinn county, tennessee, where families are counting their blessings. It's just the worst sound i ever heard in my life. Reporter: And the storm isn't done yet. In pennsylvania, blistering winds flipped this helicopter. Tonight, there will be severe weather warnings across the south. High wind, rain, expected to reach as far north as new york.

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